1. Field of the Invention
This invention relates to a highly efficient and economical method for denitration of exhaust gases.
2. Description of Prior Art
It is known to remove NO from exhaust gases by oxidation to NO.sub.2 employing NaClO, Ca(ClO).sub.2, H.sub.2 O.sub.2, KMnO.sub.4, (NH.sub.4).sub.2 S.sub.2 O.sub.5 or the like as a denitrating agent. This method, however, is insufficient from several points of view. For one, these denitrating agents are expensive; they wear away rapidly; they have a very high decomposition rate and, hence, great danger is involved in the denitration step; heavy metals contained in the denitrating agents end up in waste water, thereby causing pollution problems; and even in the case wherein an alkali metal is formed as a by-product and recovered, the cost is high and no industrial advantages accrue. Therefore, none of these known methods have been practiced industrially for nitration of boiler exhaust gases, combustion furnace exhaust gases or the like and no denitration method sufficiently applicable to industrial scale operation has heretofore been established. Nevertheless, it would be highly desirable to have such a process.